U.S. Pat. No. 3,827,765 issued Aug. 6, 1974 to Royce H. Husted discloses a brake valve construction and its associated operating linkage in somewhat schematic form. Various difficulties have been found in putting into practice the linkage disclosed in said patent. For example, it is rather difficult to obtain and maintain the desired tolerances between the various parts for the proper operation of the right and left valve poppets in the brake valve construction while maintaining the desired brake pedal free play.